ANALYTIC STUDY OF HESS ELECTRIC VEHICLE

Abstract

According to a WHO report an estimated 4.2 million people die globally due to ambient air pollution largely from heart disease, stroke, lung cancer, and acute respiratory infections in children. And unfortunately more than half of this air pollution is contributed by our transportation system. Due to zero emission of harmful greenhouse gases, quite operation, to save oil a conventional energy source for our future generations and making our country less dependent on foreign oil it has become necessary to us to move from conventional vehicles to Electric vehicles. Fortunately due to high efficiency than IC engine, cheaper to run and less maintenance electric vehicles are also a profitable alternative to conventional one. The performance of EV is mainly dependent on efficient energy storage system and effective control of power flow within its power conversion system. Batteries are the conventional energy storage element which can be used to assist IC engine in hybrid electric vehicles that are comprises of IC engine and a traction motor but due to low power density batteries alone are incapable to fulfil all desired performance characteristics like in case of acceleration and high slope operations. But a hybrid energy storage system (HESS) which consists of a battery storage unit having high energy density and an Ultra capacitors (UC) having high power density, with proper power management with the help of bidirectional DC - DC converter can be used to make EV comparable to fuel vehicles with regards to fast transient acceleration, energy, and long distance endurance. The bidirectional DC – DC converter is controlled in such a way so that batteries shares the base load like during constant speed driving interval while the Ultra capacitors are made to supply peaky load during acceleration or traction mode and to absorb the regenerated power during braking mode. The DC link voltage of the inverter is maintained constant. An indirect vector controlled induction motor is used as the propulsion unit.